Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
lang van » dang van, tang van, hoang van
van hanh » van thanh, ban hanh, van anh
su triet » su viet, su tien, ve triet
sach ky » sac ky, sach y, sach ty
hieu va » lieu va, hieu qua
cac loc » cac lop, cac toc, cac hoc
va hanh » va thanh, va danh, ban hanh
vai su » va su, van su, lai su

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: thuoc sach ky ((nang x) or (lang van)) hoi. hieu va cac loc ((va hanh) OR (van hanh)) vai su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuoc sach ky ((nang x) OR (lang van)) hoi. hieu va cac loc ((va hanh) OR (van hanh)) vai su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuoc sach ky ((nang x) or (lang van)) hoi. hieu va cac loc ((va hanh) OR (van hanh)) vai su triet".
• Adding a wildcard symbol may retrieve word variants: thuoc sach ky ((nang x) or (lang van)) hoi. hieu va cac loc ((va hanh) OR (van hanh)) vai su triet*.